OBJECTIVES: 1. In the coming year we will continue to perform serial studies of endogenous CO production as an approach to the study of hemolysis in patients with sickle cell disease in steady state. Other potential factors contributing to CO production (e.g. diet, liver function) will be examined. Further studies are planned in patients with mild pain crisis. 2. If physical exercise induces sickling in AS subjects, subsequent hemolysis may cause increased CO production. We will examine this possibility. Because the effect of exercise on CO production in healthy AA subjects is not known, these will also be studied. 3. We will continue to screen for abnormal hemoglobins all black individuals autopsied by the D. C. Medical Examiner until we reach 1000-1500 deaths from "natural causes" to see if there be excess mortality in those with sickle trait. 4. Trace metal studies in SS patients will be extended to the study of red cell carbonic anhydrase and plasma ribonuclease, both zinc containing enzymes. 5. We will continue to study unusual abnormal Hb syndromes when they are found.